How many fish in a 5 gallon tank?
The smallest size most fishkeepers recommend for a betta.
A 5 gallon tank (19 L) is too small for most schooling fish. It suits betta fish and pea puffer, kept in small numbers.
5 gallon stocking ideas
Each plan is checked by our calculator for space, water and compatibility. Add fish gradually to a cycled tank.
Betta with clean-up crew
- 1 × Betta fish
- 1 × Nerite snail
Keep the heater steady at 26 °C (79 °F) and the filter flow gentle.
Equipment for a 5 gallon tank
Sized for a 5 gallon tank (16 × 8 × 10 in) with tropical community fish. Your fish may need extras: the stocking calculator builds a list for your exact plan.
- 5 gallon aquarium (tank or kit) (opens Amazon in a new tab)Bigger tanks are more stable and easier for beginners. How to choose
- Adjustable heater, 25 W (opens Amazon in a new tab)Holds about 78 °F (25.5 °C) in a room at 68 °F (20 °C). A bigger heater can overheat a small tank if it sticks on. How to choose
- Aquarium thermometer (opens Amazon in a new tab)Check it daily: heaters can fail stuck on or off. How to choose
- Hang-on-back filter rated 20–30 GPH (opens Amazon in a new tab)Community tank: 4–6 times the tank volume per hour. How to choose
- About 15 lb of aquarium gravel (opens Amazon in a new tab)Enough for a layer about 2 in (5 cm) deep. Smooth gravel suits most community fish. How to choose
- Water conditioner (dechlorinator) (opens Amazon in a new tab)Removes chlorine and chloramine from tap water. Seachem Prime is a popular, concentrated choice. How to choose
- Liquid test kit (ammonia, nitrite, nitrate, pH) (opens Amazon in a new tab)Liquid kits are more accurate than strips. The API Freshwater Master Test Kit is the common choice. How to choose
- Gravel vacuum (siphon) (opens Amazon in a new tab)Cleans the gravel and does the water change in one go. How to choose
- LED aquarium light, about 16 in long (opens Amazon in a new tab)Match the light to the tank length. Basic LEDs grow easy plants. How to choose
Product links go to Amazon search results. As an Amazon Associate we earn from qualifying purchases, at no extra cost to you. Disclosure.
Fish that suit a 5 gallon tank
The number is the most you could keep of that species alone, by bioload. Mix species and you'll need fewer of each.
| Species | Adult size | Keep |
|---|---|---|
| Betta fish | 6.5 cm (2.6 in) | 1 male |
| Pea puffer | 2.5 cm (1 in) | 1 male + 2 or more females |
Shrimp, snails and other invertebrates
Cherry shrimp, Nerite snail, Assassin snail, Ramshorn snail, Thai micro crab.
Fish that need a bigger tank
- Angelfish: at least 29 gallons (110 L)
- Bristlenose pleco: at least 20 gallons (76 L)
- Bronze corydoras: at least 20 gallons (76 L)
- Common goldfish: at least 75 gallons (284 L)
- Common pleco: at least 150 gallons (568 L)
- Dwarf gourami: at least 15 gallons (57 L)
- Fancy goldfish: at least 20 gallons (76 L)
- Guppy: at least 10 gallons (38 L)
- Neon tetra: at least 15 gallons (57 L)
- Oscar: at least 75 gallons (284 L)
Frequently asked questions
How many fish can go in a 5 gallon tank?
A 5 gallon tank (19 L) is too small for most schooling fish. It suits betta fish and pea puffer, kept in small numbers.
What are the best fish for a 5 gallon tank?
Good choices include betta fish and pea puffer. Pick one centerpiece or one school plus a few bottom dwellers, then check the mix in our stocking calculator.
How big is a 5 gallon tank?
A standard 5 gallon tank is about 16 × 8 × 10 inches (41 × 20 × 25 cm). Full of water it weighs at least 42 lb (19 kg) before glass, gravel and decor.
What fish should not go in a 5 gallon tank?
Angelfish, bristlenose plecos, bronze corydoras, common goldfish and common plecos need more room. For example, angelfish need at least 29 gallons (110 L).
What size heater do I need for a 5 gallon tank?
About 25 W keeps a 5 gallon tank at 78 °F (25.5 °C) in a room at 68 °F (20 °C). Use a bigger heater for a colder room, or check yours with our heater size calculator.
What size filter do I need for a 5 gallon tank?
Choose a filter rated about 20–30 gallons per hour (GPH), which is 4–6 times the tank volume for a typical community tank. Messy fish like goldfish need more; bettas need gentle flow.